US20120048516A1

US20120048516A1 - Flat heat pipe with composite capillary structure

Info

Publication number: US20120048516A1
Application number: US12/869,930
Authority: US
Inventors: Sin-Wei He; Yen-Chen Chen; Ming-Cyuan Shih
Original assignee: Forcecon Technology Co Ltd
Current assignee: Forcecon Technology Co Ltd
Priority date: 2010-08-27
Filing date: 2010-08-27
Publication date: 2012-03-01

Abstract

A flat heat pipe with a composite capillary structure has a flat pipe with a flat and enclosed hollow pipe body including a top wall, a bottom wall, two lateral walls and a chamber. The flat pipe has an evaporation section and a condensation section. The elongated mesh grid is located onto either of the top and bottom walls in the chamber. The elongated mesh grid is extended from the evaporation section to the condensation section. The long porous sintered structure is located adjacent at least one lateral wall in the chamber. The long porous sintered structure is extended from the evaporation section to the condensation section. The porous sintered structure and the elongated mesh grid are prefabricated into a composite capillary structure. The flat heat pipe presents excellent diversion effect and stable positioning with its better vapor diversion space and simple manufacturing process.

Description

CROSS-REFERENCE TO RELATED U.S. APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT

Not applicable.

REFERENCE TO AN APPENDIX SUBMITTED ON COMPACT DISC

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to a flat heat pipe, and more particularly to an innovative one which is configured with a composite capillary structure and fabricated by mould pressing.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
The heat pipe is structurally configured with a capillary structure to enhance condensate return flow effectively.
A single capillary structure is employed by the conventional heat pipe to facilitate the condensate return flow, while a composite capillary structure has been developed by the industrial operators to improve the diversion effect.
Despite that said composite capillary structure can realize better condensate diversion effect, a larger problem is encountered for its manufacturing process, especially when it is applied to flat heat pipe. This is because the flat heat pipe is generally made of round pipes by means of mould pressing, the capillary structure in the pipe, whether in the form of mesh structure or sintered structure, is vulnerable to deformation, deflection and loosening during the flattening or evacuation sealing process. This results in serious problems such as: relatively higher defects and difficulty in quality control of finished products. But said composite capillary structure is involved with the mating accuracy and robustness of two capillary structures, so it is understood that the design problems become more complex and difficult with possible higher defects in the manufacturing and poorer industrial benefits.
Moreover, the thickness and space of the flat heat pipe is much less than that of the round pipe, so the vapor diversion space is reduced considerably. With the introduction of a composite capillary structure, the vapor diversion space will be further lessened for the given volume and thickness in the flat heat pipe, thus affecting its heat conduction effect.
Thus, to overcome the aforementioned problems of the prior art, it would be an advancement if the art to provide an improved structure that can significantly improve the efficacy.
Therefore, the inventor has provided the present invention of practicability after deliberate experimentation and evaluation based on years of experience in the production, development and design of related products.

BRIEF SUMMARY OF THE INVENTION

For the condensate diversion effect: with the structural configuration of the composite capillary structure wherein the elongated mesh grid is mated with the long porous sintered structure, the combined diversion structure could help realize satisfactory diversion effect.
For the positioning of the composite capillary structure: the elongated mesh grid provides an expanded positioning base for the long porous sintered structure, so that the composite capillary structure can be positioned securely. The porous sintered structure and elongated mesh grid are combined and secured to form a composite capillary structure, which is placed inside the chamber of the flat pipe, so that the composite capillary structure can be assembled to the flat pipe easily, and achieve high stability and quality.
For the vapor diversion space: given the fact that the elongated mesh grid is thin-profiled and the long porous sintered structure is located adjacent to the flat pipe's lateral wall, the present invention can provide maximum vapor diversion space for optimized heat conductance performance.
For the manufacturing process: the composite capillary structure of the present invention (composed of elongated mesh grid and a long porous sintered structure) is mated with the flat heat pipe in such a manner that the heat pipe is pre-pressed preliminarily and the elongated mesh grid is bent. When the composite capillary structure is placed, the heat pipe is pressed in place. With this configuration, it is possible to provide a simple and stable manufacturing process for mating the flat heat pipe with the composite capillary structure.
Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows an upper perspective view of the preferred embodiment of the flat heat pipe of the present invention.

FIG. 2 shows a partially exploded perspective view of the preferred embodiment of the present invention.

FIG. 3 shows a sectional view of the preferred embodiment of the present invention.

FIG. 4 shows another sectional view of the preferred embodiment of the present invention (sectional state of flat heat pipe).

FIG. 5 shows a sectional view of another preferred embodiment of the long porous sintered structure of the present invention.

FIG. 6 shows another sectional view of the preferred embodiment of the long porous sintered structure of the present invention (sectional state of flat heat pipe).

FIG. 7 shows a schematic view of the present invention wherein the elongated mesh grid is provided with a local hollowed portion.

FIG. 8 shows a schematic view of the present invention wherein the elongated mesh grid is provided with a notch.

FIG. 9 shows sectional view of another preferred embodiment of the long porous sintered structure of the present invention.

FIG. 10 shows a perspective view of the preferred embodiment in FIG. 9.

FIG. 11 shows a schematic view of the present invention wherein the long porous sintered structure is provided with a depressed portion.

FIG. 12 shows a schematic view of the present invention wherein a grooved capillary structure is formed onto the inner wall of the flat pipe.

FIG. 13 shows a schematic view of the molding process of the present invention.

FIG. 14 shows a schematic view of the other molding process of the present invention.

FIG. 15 shows a schematic view of the present invention wherein the embryo flat pipe is pre-pressed and converted from the round pipe is arranged at a local section.

FIG. 16 shows another schematic view of the long porous sintered structure of the present invention.

FIG. 17 shows another schematic view of the elongated mesh grid of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-4 depict preferred embodiments of a flat heat pipe of the present invention with a composite capillary structure, which, however, are provided for only explanatory objective for patent claims.
Said flat heat pipe A comprises a flat pipe 10, made of metal into a flat and enclosed hollow pipe body, having a top wall 11, a bottom wall 12, two lateral walls 13, 14 and a chamber 15. The flat pipe 10 has an evaporation section 16 and a condensation section 17, and both ends of the flat pipe 10 are enclosed (shown by C1, C2 in FIG. 1). Moreover, the chamber 15 is at an evacuation state. Alternatively, the chamber 15 of the flat pipe 10 is filled with working fluid.
At least one elongated mesh grid 20, made of metal, is located onto either of the top and bottom walls 11, 12 in the chamber 15 of the flat pipe 10. The elongated mesh grid 20 is extended from the evaporation section 16 to the condensation section 17 of the flat pipe 10.
At least one long porous sintered structure 30, made of metal, is located onto either position in the chamber 15 of the flat pipe 10 (the long porous sintered structure 30 of the preferred embodiment is divided into two parts adjacent to two lateral walls 13, 14). The long porous sintered structure 30 is extended from the evaporation section 16 to the condensation section 17 of the flat pipe 10.
Moreover, the porous sintered structure 30 and the elongated mesh grid 20 are prefabricated securely into a composite capillary structure B, and the composite capillary structure B is placed between the top and bottom walls 11, 12 of the chamber 15 of the flat pipe 10.
Referring to FIG. 7, a local hollowed portion 21 is formed at the central section of the elongated mesh grid 20 between the evaporation section 16 and condensation section 17 of the flat pipe 10. Moreover, a coupling surface of sintered structure 22 is reserved at the central section of the elongated mesh grid 20 for coupling the long porous sintered structure 30. In this preferred embodiment, the elongated mesh grid 20 can be further shrunk to provide a larger vapor diversion space in response to the space-saving flat heat pipe, provided that the mating state of the long porous sintered structure 30 is not affected.
Referring to FIG. 8, a single or a plurality of spacing notches 23 (V-shaped or straight pattern) is arranged at local section of the elongated mesh grid 20, in response to the bending state of the elongated mesh grid 20. When the elongated mesh grid 20 is bent in tune with the flat heat pipe, the bending portion permits one to prevent the corrugation with the configuration of said notch 23. The mesh structure will generate a corrugated surface at the bending portion without the design of notch.
Referring also to FIGS. 9 and 10, the long porous sintered structure 30 is located within the chamber 15 of the flat pipe 10 at a spacing with the lateral walls 13, 14. With this configuration, a vapor channel is formed between the long porous sintered structure 30 and lateral walls 13, 14 to improve the diversion effect. Also, the cross section of the long porous sintered structure 30 of the preferred embodiment is of a rectangular shape.
Referring to FIG. 11, at least one depressed portion 31 is formed at the local or central section of the long porous sintered structure 30. With the configuration of the depressed portion 31, the space of the vapor channel can be increased, and the long porous sintered structure 30 can be locally released to meet the bending state of the long porous sintered structure 30 when the flat heat pipe is bent. Furthermore, said depressed portion 31 is configured into either of an inclined, bended or stepped surface.
Of which, the inner wall of the flat pipe 10 is of a smooth surface (shown in FIG. 4). Alternatively, referring to FIG. 12, the inner wall of the flat pipe 10 is provided with a grooved capillary structure 18. A satisfactory condensate diversion effect can be realized via the configuration of said grooved capillary structure 18.
Based on above-specified structural configuration for the flat heat pipe of the present invention with a composite capillary structure, the molding process of the preferred embodiment is described in the following steps (referring to FIG. 13):

- (a) Prepare a round pipe 10B, one end pre-closed and the other end in open state;
- (b) Prepare at least an elongated mesh grid 20;
- (c) Prepare at least a metal powder grain 30B of long porous sintered structure, and cover it onto the elongated mesh grid 20 in a sintering mould 40;
- (d) Fix the long porous sintered structure 30 onto the surface of the elongated mesh grid 20 by means of sintering, so to as prefabricate a composite capillary structure B;
- (e) Place the prefabricated composite capillary structure B into the round pipe 10B;
- (f) Press the round pipe 10B already placed into the composite capillary structure B, and convert the round pipe 10B into a flat pipe 10D, meanwhile enabling the composite capillary structure B to be located in the flat pipe 10D adjacent to the internal plane of the flat pipe 10D;
- (g) Enable mating of the composite capillary structure B and flat pipe 10D by means of sintering;
- (h) Fill working fluid into the flat pipe 10D and then evacuate it for sealing.

Alternatively, another molding process of the preferred embodiment is described in the following steps (referring to FIG. 14):

- (a) Prepare a metal round pipe 10B, one end pre-closed and the other end in open state;
- (b) Prepare at least an elongated mesh grid 20;
- (c) Prepare at least a metal powder grain 30B of long porous sintered structure, and cover it onto the elongated mesh grid 20 in a sintering mould 40;
- (d) Fix the long porous sintered structure 30 onto the surface of the elongated mesh grid 20 by means of sintering, so to as prefabricate a composite capillary structure B;
- (e) Bend the elongated mesh grid 20 of the composite capillary structure B so as to form a bending portion on the elongated mesh grid 20;
- (f) Pre-press the round pipe 10B for the first time to convert the round pipe 10B into an embryo flat pipe 10C, but the degree of pressing only reaches 60%-90% of the preset degree;
- (g) Place the composite capillary structure B into the round pipe 10C obtained in aforementioned step (d);
- (h) Press again the embryo flat pipe 10C already placed into the composite capillary structure B, and convert it into a shaped flat pipe 10D, meanwhile enabling the long porous sintered structure 30 of the composite capillary structure B to be located onto the lateral wall of the flat pipe 10D adjacent to the internal plane of the flat pipe 10D, and also enabling the bending portion 24 of the elongated mesh grid 20 to be extended into a straight or nearly straight shape;
- (i) Enable mating of the composite capillary structure B and flat pipe 10D (by means of sintering);
- (j) Fill working fluid into the flat pipe 10D and then evacuate it for sealing, thereby fabricating a finished flat heat pipe of present invention with composite capillary structure.

In the above methods, the long porous sintered structure 30 of the composite capillary structure B is preferably fixed at two sides on the surface of the elongated mesh grid 20.
Moreover, for the embryo flat pipe 10C pre-pressed by the round pipe 10B, its flat cross section is pressed by full section. Alternatively, referring to FIG. 15, the flat cross section is pressed by partial section. The pre-pressed flat cross section is used for preventing overturn and displacement of composite capillary structure B not yet sintered.
Referring to FIG. 16, corrugated surface expanded portions 32 (rectangular, bended, stepped and reversed shapes) are formed onto one or two sides of the long porous sintered structure 30, so the evaporation effect of the working fluid for the long porous sintered structure 30 can be improved to obtain better heat conduction efficiency.
Referring to FIG. 17, said elongated mesh grid can be placed in the interval space between the top and bottom walls 11, 12 of the chamber 15 of the flat pipe 10.

Claims

1. A flat heat pipe with composite capillary structure, comprising:

a flat pipe, made of metal into a flat and enclosed hollow pipe body having a top wall, a bottom wall, two lateral walls and a chamber; the flat pipe having an evaporation section and a condensation section, and both ends of the flat pipe are enclosed; moreover, the chamber is at an evacuation state; alternatively, the chamber of the flat pipe is filled with working fluid;

an elongated mesh grid, made of metal, located in the chamber of the flat pipe; the elongated mesh grid is extended from the evaporation section to the condensation section of the flat pipe;

a long porous sintered structure, made of metal, located onto either position in the chamber of the flat pipe; the long porous sintered structure is extended from the evaporation section to the condensation section of the flat pipe;

the porous sintered structure and the elongated mesh grid are prefabricated securely into a composite capillary structure, and the composite capillary structure is placed between the top and bottom walls of the chamber of the flat pipe.

2. The structure defined in claim 1, wherein a local hollowed portion is formed at the central section of the elongated mesh grid between the evaporation section and condensation section of the flat pipe; moreover, a coupling surface of sintered structure is reserved at the central section of the elongated mesh grid for coupling the long porous sintered structure.

3. The structure defined in claim 1, wherein a single or a plurality of spacing notches is arranged at local section of the elongated mesh grid, in response to the bending state of the elongated mesh grid.

4. The structure defined in claim 1, wherein at least a depressed portion is formed at the local or central section of the long porous sintered structure; said depressed portion is configured into either of an inclined, bended or stepped surface.

5. The structure defined in claim 1, wherein the long porous sintered structure is located adjacent to two lateral walls, or one lateral wall, or at a spacing with the lateral wall in the chamber of the flat pipe.

6. The structure defined in claim 1, wherein the inner wall of the flat pipe is provided with a smooth surface or a grooved capillary structure.

7. The structure defined in claim 1, wherein said corrugated surface expanded portions are formed onto one or two sides of the long porous sintered structure, so as to improve the evaporation effect of the working fluid for the long porous sintered structure.

8. The structure defined in claim 1, wherein the and the elongated mesh grid is placed between the top and bottom walls of the chamber of the flat pipe, and at one is placed at the interval space between the top and bottom walls.

9. The structure defined in claim 1, wherein the molding process of the flat heat pipe comprises the following steps:

(a) preparing a round pipe, one end pre-closed and the other end in open state;

(b) preparing an elongated mesh grid;

(c) preparing a metal powder grain of long porous sintered structure, and covering it onto the elongated mesh grid in a sintering mould;

(d) fixing the long porous sintered structure onto the surface of the elongated mesh grid by means of sintering, so to as prefabricate a composite capillary structure;

(e) placing the prefabricated composite capillary structure into the round pipe;

(f) pressing the round pipe already placed into the composite capillary structure, and convert the round pipe into a flat pipe, meanwhile enabling the composite capillary structure to be located in the flat pipe adjacent to the internal plane of the flat pipe;

(g) filling working fluid into the flat pipe and then evacuating said flat pipe for sealing.

10. The structure defined in claim 9, wherein the elongated mesh grid of the composite capillary structure is bent to form a bending portion before the composite capillary structure is placed into the round pipe; then the round pipe is pre-pressed and bent to convert the round pipe into an embryo flat pipe, but the degree of pressing only reaches 60-90% of the preset degree; the composite capillary structure is then placed into the embryo flat pipe; then the embryo flat pipe is pressed again to convert itself into a flat pipe, meanwhile enabling the bending portion of the elongated mesh grid to be extended into a straight or nearly straight shape.

11. The structure defined in claim 9, wherein the round pipe is pre-pressed to convert into an embryo flat pipe, with the flat cross section pressed by full or partial section.

12. The structure defined in claim 9, wherein the composite capillary structure and the flat pipe are mated by means of sintering before the flat pipe is filled with working fluid and evacuated for sealing.